Semi-removable Mass Stove

Tutorial de avatarLow-tech Lab | Categories : Housing, Energy

Semi-removable inertia mass stove. A mass storage stove or ‘heat storage stove’ is a primary heating device. Its mass, which is made up of heavy material (stone, brick and concrete), stores energy from a fire that burns once during the day (lasting between 1 and 3 hours). Once the fire has gone out, it then continues to give out heat over a prolonged period (for up to 24 hours). Its mass provides thermal inertia which helps to keep an even temperature inside a building (which is why these stoves are often also called “inertia stoves”). The whole of the quantity of wood needed to heat the dwelling is burnt in one go, making it burn hotter which allows complete and more environmentally-friendly combustion. It is a storage device which is designed to absorb the bulk of the energy that is generated from combustion and exhaust gases, which cool down considerably once out of the stove. Accumulated heat is mainly diffused by radiation and, in a few cases, by convection. This particular type of heating, i.e. that uses radiation, is best located in the centre of the dwelling and therefore, most mass stoves these days are positioned in the main room which opens out onto the lounge, dining room and kitchen. As yield tends tend to be in the majority of cases higher than 80%, these stoves are considered to be one of the most efficient wood-fuelled heating devices. Watch the tutorial video here [2]

License : Attribution-ShareAlike (CC BY-SA)

Video overview



  • Metal drum
* Pipework (tubes of differing diameters and T-tube) 
  • Sewer grate


  • Self-tapping screws,
  • Nuts and bolts


  • Tamper for packing down and applying the concrete,
  • Wire,
  • An old cloth to put in the drum to deaden the noise whilst you are working.


  • Plastic packaging (cellophane),
  • Gaffer tape
  • Masking tape,
  • Corrugated cardboard,
  • Cardboard tubes of 80, 100, 130mm diameters respectively


Health and Safety:

  • Gloves,
  • Goggles,
  • Ear defenders/ earplugs,
  • Dust masks
  • First aid kit containing saline solution in case cements gets into eyes.

For Marking/Measuring:

  • Tape measure,
  • Pencil,
  • Marker
  • String (2 metres approx.),
  • Spirit level

For the Metalwork:

  • Hammer/sledgehammer/chisel,
  • Pincers
  • Adjustable pliers
  • Tin snips (often more practical that using an electric device)
  • Jigsaw + metal blades
  • Clamp
  • Drill + metal drill bits
  • Wire brush for drill
  • Angle grinder + cutting, grinding and flap disks,
  • Sander (optional)


  • Tarpaulin
  • 1 litre measuring cup,
  • Trowel
  • 2 x 10 litre buckets, mixing tray, container or bin for mixing concrete
  • Hand mixer
  • Power drill with paddle or manual mixer or cement mixer (optional)


  • Cutter,
  • Scissors,
  • Handsaw

Step 1 - Provision of Materials

Step 2 - How the Device is made up:

The idea behind the Poelito is to build a rocket stove inside a drum. The bottom of the drum is lined with an insulating mix of concrete; however the stove still needs to stand on a fire-proof support.The bottom part of the stove is cast in refractory concrete around a mould made of cardboard tubes. This is the area where the fire develops.Tubes are used to make the hollowed-out conduits: these are the routes which the smoke and fire take. The lower part forms the base of the fire pit and is a fixed body of material. The upper half is made up of removable metal pipes and is filled up with sand. This can either be left standing or transported separately. The fire pit can be closed to the outside either by a cast iron plate or by a pane of ceramic glass which can then be covered over by the drum lid as a finishing touch. The exhaust pipe is on the outside of the drum to which connection is made by a T joint with cap for cleaning out. Any pipes that go along the ceiling and to roof vents (or anything which goes outside of the dwelling) must be insulated.

In the picture, you can see the bottom of the vertical feed pipe and the ash tray at the front and, behind, the pipe where the fire is lit . This together forms the burner. Towards the back, there are 2 pipes where the smoke is forced down. These are situated on either side of the pipe where the fire lit. These pipes join up underneath by means of a manifold which directs the smoke towards the back in the direction of the smoke exhaust which forms the manifold. Connection to the exhaust pipe is by means of a T with cap.

Step 3 - Sizingː

Step 4 - Fundamental Health and Safety Rules

Step 5 - Different types of Concrete: how to make them up and what goes in them.

Step 6 - Preparing the drum

Step 7 - Making the Ash Tray and Smoke Exhaust Holes

Step 8 - Fitting the Ash Tubes and Smoke Exhaust

Step 9 - Fitting the Moulds

Step 10 - Making the stopper for the ash tray

Step 11 - Casting the protective bottom

Step 12 - Making the Moulds

Step 13 - Positioning the Moulds.

Step 14 - Pouring the Refractory Concrete

Step 15 - Removing the Moulds

Step 16 - How to Make the Wood Feed Pipe.

Step 17 - How to make the Wood Feed Stopper

Step 18 - Making the Grate

Step 19 - How to Make the Heat Riser.

Step 20 - Making the Bell Chamber

Step 21 - Cutting out the glass

Step 22 - Cutting out the lid

Step 23 - Painting

Step 24 - Installation

Step 25 - Filling it up with sand

Step 26 - Fitting the glass

Step 27 - Directions for use

Step 28 - Maintenance